Preprocessing of epoched EEG and MEG data usually involves the following steps: filtering & segmentation (extracting event related data epochs from the continuous signal), artefact detection & correction   and event related averaging. For EEG data, the calculation of an average reference may also be required.  These steps are described on the pages of this section.

  Wavelet analysis and single trial activation analysis also require the standards steps to be performed, as they are based on clean  data and are heavily disrupted by artefactual segments.